Montanastatin, cyclo[-(Val-D-Hyv-D-Val-Lac)₂-]

Crystals of montanastatin anhydride, C₃₆H₆₀N₄O₁₂, were grown from a hexyl­ene glycol solution. A crystallographic twofold axis runs through the centre of the mol­ecule. The aliphatic side chains located on one side of the peptide ring form a hydro­phobic region. The shape of the whole mol­ecule is rectangular and is similar to the structure of the valinomycin analogue, viz. cyclo[-(D-Val-L-Hyv-L-Val-D-Hyv)₂-].

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.049
• wR factor = 0.111
• Data-to-parameter ratio = 19.5

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



ABSTM_02  Alert C The ratio of expected to reported Tmax/Tmin(RR') is < 0.90
          Tmin and Tmax reported:      0.854     0.982
          Tmin' and Tmax expected:      0.970     0.982
          RR' =      0.881
          Please check that your absorption correction is appropriate.

STRVAL_01
         From the CIF: _refine_ls_abs_structure_Flack    0.100
         From the CIF: _refine_ls_abs_structure_Flack_su    0.900
           Alert C Flack test results are meaningless.

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           28.60
         From the CIF: _reflns_number_total               4717
         Count of symmetry unique reflns         2805
         Completeness (_total/calc)            168.16%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured      1912
         Fraction of Friedel pairs measured     0.682
         Are heavy atom types Z>Si present           no
          ALERT: MoKa measured Friedel data cannot be used to
                 determine absolute structure in a light-atom
                 study EXCEPT under VERY special conditions.
                 It is preferred that Friedel data is merged in such cases.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 2 Alert Level C = Please check

---

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT-Plus (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2001); software used to prepare material for publication: PARST (Nardelli, 1995).

Montanastatin: cyclo(–Val-D-Hyv-D-Val-Lac-)2, Hyv=alpha-hydroxyisovaleric acid, Lac=lactic acid

Crystal data

C36H60N4O12	Dx = 1.241 Mg m^−3
Mr = 740.88	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, C2221	Cell parameters from 3994 reflections
a = 13.488 (6) Å	θ = 2.3–28.0°
b = 17.868 (7) Å	µ = 0.09 mm^−1
c = 16.452 (7) Å	T = 100 K
V = 3965 (3) Å^3	Block, colourless
Z = 4	0.32 × 0.24 × 0.20 mm
F(000) = 1600

Data collection

Bruker AXS SMART APEX CCD diffractometer	4717 independent reflections
Radiation source: MacScience, M18XCE rotating anode	4545 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
Detector resolution: 8.366 pixels mm^-1	θmax = 28.6°, θmin = 1.9°
ω scans	h = −17→17
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	k = −15→23
Tmin = 0.854, Tmax = 0.982	l = −22→22
13003 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.049	H-atom parameters constrained
wR(F^2) = 0.111	w = 1/[σ^2(Fo^2) + (0.0472P)^2 + 1.956P] where P = (Fo^2 + 2Fc^2)/3
S = 1.18	(Δ/σ)max < 0.001
4717 reflections	Δρmax = 0.32 e Å^−3
242 parameters	Δρmin = −0.22 e Å^−3
0 restraints	Absolute structure: (Flack, 1983), 1912 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.1 (9)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
ON_4	0.75840 (10)	0.75068 (8)	0.64983 (7)	0.0171 (3)
CA_4	0.71119 (15)	0.77521 (11)	0.72391 (11)	0.0182 (4)
H1_4	0.7622	0.7910	0.7646	0.022*
CB_4	0.64520 (19)	0.84027 (12)	0.70235 (13)	0.0272 (5)
H2_4	0.5964	0.8244	0.6617	0.041*
H3_4	0.6855	0.8810	0.6801	0.041*
H4_4	0.6107	0.8578	0.7512	0.041*
C_4	0.65235 (13)	0.70761 (10)	0.75589 (11)	0.0139 (4)
O_4	0.62526 (11)	0.65716 (8)	0.71054 (8)	0.0187 (3)
N_1	0.63456 (12)	0.71050 (9)	0.83575 (9)	0.0145 (3)
H5_1	0.6545	0.7501	0.8630	0.017*
CA_1	0.58414 (13)	0.65153 (10)	0.87941 (10)	0.0125 (4)
H6_1	0.5427	0.6227	0.8399	0.015*
CB_1	0.65766 (14)	0.59673 (11)	0.92044 (12)	0.0158 (4)
H7_1	0.6186	0.5624	0.9563	0.019*
CG1_1	0.73278 (15)	0.63802 (13)	0.97357 (12)	0.0212 (4)
H8_1	0.7744	0.6701	0.9393	0.032*
H9_1	0.7746	0.6016	1.0020	0.032*
H10_1	0.6976	0.6689	1.0134	0.032*
CG2_1	0.71070 (16)	0.54893 (12)	0.85690 (13)	0.0228 (4)
H11_1	0.7527	0.5119	0.8843	0.034*
H12_1	0.7519	0.5811	0.8225	0.034*
H13_1	0.6615	0.5231	0.8232	0.034*
C_1	0.51590 (13)	0.68775 (11)	0.94122 (10)	0.0127 (4)
O_1	0.51084 (11)	0.75341 (8)	0.95480 (8)	0.0192 (3)
ON_2	0.46187 (9)	0.63488 (7)	0.97993 (7)	0.0130 (3)
CA_2	0.40142 (13)	0.65922 (10)	1.04793 (10)	0.0129 (3)
H14_2	0.4171	0.7130	1.0587	0.015*
CB_2	0.43088 (14)	0.61425 (11)	1.12323 (11)	0.0149 (4)
H15_2	0.3845	0.6282	1.1681	0.018*
CG1_2	0.42158 (16)	0.53035 (11)	1.10937 (12)	0.0215 (4)
H16_2	0.4730	0.5139	1.0713	0.032*
H17_2	0.3561	0.5191	1.0867	0.032*
H18_2	0.4296	0.5040	1.1612	0.032*
CG2_2	0.53535 (15)	0.63533 (14)	1.14983 (12)	0.0258 (5)
H19_2	0.5371	0.6885	1.1645	0.039*
H20_2	0.5818	0.6261	1.1051	0.039*
H21_2	0.5544	0.6050	1.1970	0.039*
C_2	0.29184 (13)	0.65372 (10)	1.02782 (11)	0.0131 (3)
O_2	0.23148 (10)	0.66612 (8)	1.08159 (8)	0.0179 (3)
N_3	0.26771 (11)	0.63797 (9)	0.95056 (9)	0.0150 (3)
H22_3	0.3130	0.6197	0.9176	0.018*
CA_3	0.16727 (13)	0.65071 (11)	0.92056 (11)	0.0159 (4)
H23_3	0.1337	0.6850	0.9599	0.019*
CB_3	0.10523 (15)	0.57892 (12)	0.91610 (13)	0.0224 (4)
H24_3	0.1112	0.5540	0.9703	0.027*
CG1_3	0.14135 (18)	0.52245 (14)	0.85321 (15)	0.0321 (5)
H25_3	0.2139	0.5203	0.8543	0.048*
H26_3	0.1191	0.5378	0.7990	0.048*
H27_3	0.1142	0.4729	0.8659	0.048*
CG2_3	−0.00444 (18)	0.59678 (15)	0.90426 (16)	0.0347 (5)
H28_3	−0.0432	0.5505	0.9078	0.052*
H29_3	−0.0143	0.6197	0.8507	0.052*
H30_3	−0.0263	0.6316	0.9466	0.052*
C_3	0.82219 (14)	0.69313 (11)	0.65939 (12)	0.0172 (4)
O_3	0.86226 (11)	0.67840 (9)	0.72215 (8)	0.0251 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
ON_4	0.0204 (7)	0.0194 (7)	0.0114 (6)	−0.0043 (6)	0.0024 (5)	0.0013 (6)
CA_4	0.0237 (10)	0.0203 (9)	0.0107 (8)	−0.0074 (8)	0.0026 (7)	−0.0019 (7)
CB_4	0.0399 (13)	0.0184 (10)	0.0232 (11)	−0.0028 (9)	0.0080 (9)	0.0007 (8)
C_4	0.0111 (8)	0.0175 (9)	0.0130 (8)	−0.0014 (7)	−0.0001 (7)	−0.0003 (7)
O_4	0.0223 (7)	0.0211 (7)	0.0126 (6)	−0.0090 (6)	0.0014 (5)	−0.0021 (5)
N_1	0.0175 (7)	0.0149 (8)	0.0112 (7)	−0.0053 (6)	0.0018 (6)	−0.0019 (6)
CA_1	0.0128 (8)	0.0148 (9)	0.0098 (8)	−0.0043 (7)	−0.0004 (6)	−0.0003 (7)
CB_1	0.0146 (9)	0.0163 (9)	0.0165 (9)	0.0008 (7)	0.0014 (7)	0.0023 (7)
CG1_1	0.0178 (9)	0.0288 (11)	0.0170 (9)	0.0007 (8)	−0.0022 (7)	0.0013 (8)
CG2_1	0.0227 (10)	0.0224 (11)	0.0233 (10)	0.0051 (8)	0.0042 (8)	−0.0016 (8)
C_1	0.0122 (9)	0.0177 (9)	0.0081 (7)	−0.0026 (7)	−0.0034 (6)	0.0025 (7)
O_1	0.0235 (7)	0.0143 (7)	0.0199 (6)	−0.0041 (6)	0.0056 (6)	−0.0005 (6)
ON_2	0.0138 (6)	0.0136 (6)	0.0117 (6)	−0.0019 (5)	0.0035 (5)	−0.0006 (5)
CA_2	0.0156 (8)	0.0139 (9)	0.0092 (8)	−0.0003 (7)	0.0033 (7)	−0.0016 (7)
CB_2	0.0142 (9)	0.0210 (10)	0.0096 (8)	0.0014 (7)	0.0018 (7)	0.0008 (7)
CG1_2	0.0262 (11)	0.0191 (10)	0.0193 (10)	0.0031 (8)	0.0023 (8)	0.0059 (8)
CG2_2	0.0176 (9)	0.0455 (14)	0.0143 (9)	−0.0052 (9)	−0.0019 (8)	0.0001 (9)
C_2	0.0160 (8)	0.0098 (8)	0.0136 (8)	0.0033 (7)	0.0016 (7)	0.0002 (7)
O_2	0.0184 (7)	0.0235 (7)	0.0117 (6)	0.0075 (6)	0.0023 (5)	−0.0009 (5)
N_3	0.0129 (7)	0.0201 (8)	0.0121 (7)	0.0052 (6)	0.0012 (6)	−0.0012 (6)
CA_3	0.0130 (8)	0.0221 (10)	0.0126 (8)	0.0037 (7)	0.0010 (7)	−0.0030 (7)
CB_3	0.0204 (10)	0.0254 (11)	0.0213 (10)	−0.0008 (8)	−0.0016 (8)	0.0016 (8)
CG1_3	0.0309 (12)	0.0277 (12)	0.0376 (13)	0.0014 (10)	−0.0079 (10)	−0.0066 (10)
CG2_3	0.0213 (11)	0.0444 (14)	0.0384 (13)	−0.0061 (11)	0.0048 (10)	−0.0116 (11)
C_3	0.0149 (9)	0.0204 (10)	0.0163 (9)	−0.0089 (7)	0.0027 (7)	0.0022 (8)
O_3	0.0254 (8)	0.0344 (9)	0.0154 (7)	−0.0020 (7)	−0.0063 (6)	−0.0009 (6)

Geometric parameters (Å, º)

ON_4—C_3	1.350 (3)	CA_2—C_2	1.518 (3)
ON_4—CA_4	1.443 (2)	CA_2—CB_2	1.529 (3)
CA_4—CB_4	1.506 (3)	CB_2—CG1_2	1.521 (3)
CA_4—C_4	1.538 (3)	CB_2—CG2_2	1.523 (3)
C_4—O_4	1.226 (2)	C_2—O_2	1.222 (2)
C_4—N_1	1.336 (2)	C_2—N_3	1.342 (2)
N_1—CA_1	1.445 (2)	N_3—CA_3	1.460 (2)
CA_1—C_1	1.517 (2)	CA_3—C_3^i	1.525 (3)
CA_1—CB_1	1.548 (3)	CA_3—CB_3	1.533 (3)
CB_1—CG2_1	1.528 (3)	CB_3—CG1_3	1.525 (3)
CB_1—CG1_1	1.528 (3)	CB_3—CG2_3	1.526 (3)
C_1—O_1	1.196 (2)	C_3—O_3	1.195 (2)
C_1—ON_2	1.353 (2)	C_3—CA_3^i	1.525 (3)
ON_2—CA_2	1.451 (2)
C_3—ON_4—CA_4	114.46 (15)	ON_2—CA_2—CB_2	108.72 (15)
ON_4—CA_4—CB_4	107.23 (16)	C_2—CA_2—CB_2	113.31 (15)
ON_4—CA_4—C_4	106.14 (15)	CG1_2—CB_2—CG2_2	111.29 (17)
CB_4—CA_4—C_4	112.43 (17)	CG1_2—CB_2—CA_2	112.03 (16)
O_4—C_4—N_1	124.97 (17)	CG2_2—CB_2—CA_2	110.08 (16)
O_4—C_4—CA_4	121.54 (17)	O_2—C_2—N_3	124.19 (17)
N_1—C_4—CA_4	113.49 (15)	O_2—C_2—CA_2	118.62 (16)
C_4—N_1—CA_1	123.02 (15)	N_3—C_2—CA_2	117.14 (15)
N_1—CA_1—C_1	107.92 (15)	C_2—N_3—CA_3	120.84 (16)
N_1—CA_1—CB_1	112.11 (15)	N_3—CA_3—C_3^i	106.43 (15)
C_1—CA_1—CB_1	111.49 (14)	N_3—CA_3—CB_3	113.09 (16)
CG2_1—CB_1—CG1_1	110.54 (17)	C_3^i—CA_3—CB_3	115.18 (16)
CG2_1—CB_1—CA_1	110.80 (16)	CG1_3—CB_3—CG2_3	111.19 (19)
CG1_1—CB_1—CA_1	111.63 (16)	CG1_3—CB_3—CA_3	114.31 (18)
O_1—C_1—ON_2	124.50 (17)	CG2_3—CB_3—CA_3	111.11 (18)
O_1—C_1—CA_1	125.34 (16)	O_3—C_3—ON_4	123.83 (19)
ON_2—C_1—CA_1	110.16 (15)	O_3—C_3—CA_3^i	126.43 (19)
C_1—ON_2—CA_2	117.15 (14)	ON_4—C_3—CA_3^i	109.73 (15)
ON_2—CA_2—C_2	111.08 (14)
C_3—On_4—Ca_4—Cb_4	178.6 (2)	O_1—C_1—On_2—Ca_2	−6.5 (3)
C_3—On_4—Ca_4—C_4	−61.0 (2)	C_1—On_2—Ca_2—Cb_2	−123.2 (2)
Ca_4—On_4—C_3—O_3	−23.4 (3)	C_1—ON_2—Ca_2—C_2	111.4 (2)
On_4—Ca_4—C_4—O_4	−23.4 (2)	On_2—Ca_2—Cb_2—Cg1_2	−56.5 (2)
ON_4—Ca_4—C_4—N_1	156.9 (2)	On_2—Ca_2—Cb_2—Cg2_2	67.9 (2)
Cb_4—Ca_4—C_4—O_4	93.5 (2)	C_2—Ca_2—Cb_2—Cg1_2	67.6 (2)
Cb_4—Ca_4—C_4—N_1	−86.2 (2)	C_2—Ca_2—Cb_2—Cg2_2	−168.1 (2)
Ca_4—C_4—N_1—Ca_1	−177.4 (2)	On_2—Ca_2—C_2—O_2	173.7 (2)
O_4—C_4—N_1—Ca_1	3.0 (3)	ON_2—Ca_2—C_2—N_3	−8.6 (2)
C_4—N_1—Ca_1—Cb_1	96.2 (2)	Cb_2—Ca_2—C_2—O_2	51.0 (2)
C_4—N_1—Ca_1—C_1	−140.6 (2)	Cb_2—Ca_2—C_2—N_3	−131.3 (2)
N_1—Ca_1—Cb_1—Cg1_1	53.0 (2)	Ca_2—C_2—N_3—Ca_3	−163.8 (2)
N_1—Ca_1—Cb_1—Cg2_1	−70.7 (2)	O_2—C_2—N_3—Ca_3	13.8 (3)
C_1—Ca_1—Cb_1—Cg1_1	−68.1 (2)	C_2—N_3—Ca_3—Cb_3	−101.1 (2)
C_1—Ca_1—Cb_1—Cg2_1	168.2 (2)	N_3—Ca_3—Cb_3—Cg1_3	−66.7 (2)
N_1—Ca_1—C_1—O_1	−4.9 (3)	N_3—Ca_3—Cb_3—Cg2_3	166.5 (2)
N_1—Ca_1—C_1—ON_2	175.8 (1)	C_2—N_3—Ca_3—C_3^i	131.6 (2)
Cb_1—Ca_1—C_1—O_1	118.6 (2)	N_3—Ca_3—C_3^i—ON_4^i	−47.7 (2)
Cb_1—Ca_1—C_1—On_2	−60.7 (2)	Ca_3—C_3^i—ON_4^i—Ca_4^i	155.7 (1)
Ca_1—C_1—ON_2—Ca_2	172.8 (1)

Symmetry code: (i) −x+1, y, −z+3/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N_1—H5_1···O_2^ii	0.88	2.04	2.901 (2)	167
N_3—H22_3···O_4^i	0.88	2.36	3.037 (2)	134

Symmetry codes: (i) −x+1, y, −z+3/2; (ii) x+1/2, −y+3/2, −z+2.